The brooks b4 frame bag a classic leather bag with three attachment straps and metal buckles designed to be slung beneath the top tube of your bicycle frame and held snugly in place against the seat tube the deep outer closing flap is opened or closed with a buckle and strap fed through two hard wearing metal eyelets brooks b4 frame bag features made from vegetable tanned brooks leather made in england volume 085l width 120mm depth 40mm height 180mm